1. Field of the Invention
The present invention relates to devices for ultrasonic surgical probes or scalpels for use in the removal of inorganic or organic tissue from a living body, and, more particularly, to a device adapted to be installed within an ultrasonic surgical tool capable of reducing the formation of bubbles imparting ultrasonic vibrations in the stream of irrigating or other fluid flowing to the operating needle of the tool.
2. Description of Related Art
Ultrasonic probes or scalpels for the fragmentation and removal of inorganic materials and fluids from living beings have been long known to the art. For example, U.S. Pat. No. 2,227,727, issued Jan. 7, 1941 to Vincent Leggiardro, discloses an apparatus having a two part housing, with a sonic transducer in one part and a reciprocating rod in another part, for fragmenting naturally formed stones, such as bladder stones, kidney stones, and the like. In later apparatus the transducer and probe were connected together to form a unitary instrument. For example, in U.S. Pat. No. 3,896,811, issued Jul. 29, 1975 to Karl Storz, the transducer and rod-like probe are coupled and both are enveloped by a jacket providing an air gap and preventing the sides of the probe from contacting the body except at its end.
An improvement in such instruments is disclosed in U.S. Pat. No. 3,990,452, issued Nov. 9, 1976 to Edward J. Murry and Joseph F. Brumbach, which also reviews a number of articles relating to the development of ultrasonics in medicine and, particularly for use in cataract surgery, and notes the incorporation of irrigation and aspiration with ultrasonics.
The use of irrigating fluid flowing to the needle in an ultrasonically vibrated surgical tool and flowing to the operating site is now widely used, particularly for ophthalmic surgery. However, the passage, of the irrigation fluid about the ultrasonically vibrating needle and connectors between the needle and the ultrasonic transducer, frequently causes the formation of cavitation bubbles in the stream of flowing irrigation fluid. These bubbles decrease the efficiency of the fluid where the fluid is utilized to cool the needle, and creates a visual obstruction to the surgeon at the operating site in delicate surgery where the irrigating fluid is directed to the operating site.
To reduce the formation or the passage of cavitation bubbles from the ultrasonically vibrating parts of the tool and particularly their passage to the operating site, various devices have been included in the tool. For example, the use of a circular diaphragm with openings positioned in the fluid path at a point prior to the fluid contacting the needle is disclosed in U.S. Pat. No. 4,428,748, issued Jan. 31, 1984 to Gholam A. Peyman, et. al. In two U.S. Pat. Nos. 4,681,561 and 4,816,017, issued Jul. 21, 1987, and Mar. 28, 1989, respectively, to Larry L. Hood and Maurice M. Imonti, a decoupling sleeve having a collar portion is placed in the irrigating fluid path about the ultrasonically vibrated tool or needle and by means of the collar is retained within the interior of a tip cap sleeve member, the sleeve impeding the transmission of ultrasonic energy through the fluid as the fluid passes through the sleeve. In another U.S. Pat. No. 5,151,084, issued Sep. 29, 1992, to Sokhuom Khek, a disk-shaped baffle with holes is positioned in the fluid path about the needle after contact with the ultrasonic motor and the connectors between the motor and the needle to reduce bubbles in the fluid as the fluid passes through the baffle and to improve the visibility at the operating site.
However, none of these arrangements are completely satisfactory to reduce the presence of bubbles in the irrigating fluid supplied to the needle, to cool the latter, and to the operating site. Therefore, there is a need for an improved ultrasonic surgical tool construction which provides for improved reduction in the amount of bubbles in the irrigating fluid supplied to the needle and exiting from the fluid passage surrounding the needle to the surgical site.